<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .box {
        border: 3px solid #000000;
        border-radius: 10px;
        padding: 20px;
        margin: 20px;
        width: 200px;
      }
      h3 {
        margin: 10px 0 20px 0;
      }
      p {
        margin: 20px;
      }
    </style>
  </head>
  <body>
    <div id="app">
      <div class="box">
        <h3>小黑自动售货机</h3>
        <!-- 调用函数传递 实参 -->
        <button @click="buy(5)">可乐5元</button>
        <button @click="buy(10)">咖啡10元</button>
        <button @click="buy(8)">牛奶8元</button>
      </div>
      <p>银行卡余额：{{ money }}元</p>
    </div>

    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <script>
      const app = new Vue({
        el: "#app",
        data: {
          money: 100,
        },
        methods: {
          // 事件处理函数 形参
          buy(price) {
            // 推荐使用this 指向Vue实例
            this.money -= price;
          },
        },
      });
    </script>
  </body>
</html>
